Cu nanoparticles of size 5-10 nm supported on MgÀ Al mixed oxide were prepared by the sol-gel method. Cu loading was varied from 2.5 to 10 wt % on the support to investigate the effect on particle size and activity/selectivity of the catalyst. The Cu/MgÀ Al catalysts containing small copper nanoparticles favor high selectivity of methanol, while the rate of CO formation was higher for larger copper particles. The high methanol selectivity (~99 %) and methanol formation rate (0.016 mol g Cu À 1 h À 1 ) over the 4.8Cu/MgÀ Al catalyst was due to the combined effect of the presence of high Cu dispersion, Cu surface area, and strong interaction between small Cu particles with MgÀ Al support. The high stability of the catalyst was attributed to the strong binding of the Cu cluster (À 179.7 kJ/mol) to the MgO/γ-Al 2 O 3 support, as shown by the DFT study. Additionally, the adsorption energy calculated using DFT showed preferential adsorption of CO 2 and H 2 at the Cu/MgO(100) active site (À 120.9 kJ/mol, À 130.4 kJ/mol) compared to the Cu/γ-Al 2 O 3 (100) (À 64.2 kJ/mol, À 85.7 kJ/mol)active site. The high selectivity of the catalyst towards methanol can be attributed to the higher stability of the formate (HCOO) intermediate (À 257.2 kJ/mol) compared to the carboxylate (COOH) intermediate (À 131.0 kJ/mol).

Here we demonstrate a simple and cost effective synthetic route for selective esterification of aldehydes with high productivity in the presence of molecular oxygen (O 2 ) on a gold supported lanthanum oxide (Au/La 2 O 3 ) nanoparticle catalyst. Au nanoparticles with sizes of 2−7 nm supported on 1D La 2 O 3 nanorods with diameters between 20 and 50 nm were synthesized by a room-temperature surfactantassisted single-step preparation method. The as-synthesized catalyst was thoroughly characterized by powder XRD, SEM, HR-TEM, H 2 -TPR, XPS, TGA/DTA, FTIR, BET, EXAFS, and UV−visible spectroscopy. This prepared nanostructured catalyst was found to be highly effective in the liquid phase synthesis of methyl methacrylate (MMA) via direct oxidative esterification of methacrolein (MA) with a high turnover number of ∼1136. The effect of various reaction controlling parameters like reaction temperature, pressure, and time of reaction was investigated and studied. High methacrolein conversion of 89% with high methyl methacrylate selectivity of 98% was attained without the use of any external additives. The synergistic effect between the surface AuNPs and La 2 O 3 nanorods plays an important role toward the activity of the catalyst.

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